1. Field of the Invention
The present invention relates to an organic electroluminescent device and a method of manufacturing the same. More particularly, the present invention relates to an organic electroluminescent device using a porous oxide layer for adsorbing moisture and oxygen, and a method of manufacturing the same.
2. Discussion of the Related Art
Organic electroluminescent devices (organic EL devices) are self emissive displays that emit light by recombination of electrons and holes in an organic thin layer when a current is applied to the thin layer. Organic EL devices are lightweight, have simple constitutional elements, are easily fabricated, and they have superior image quality and a wide viewing angle. Additionally, organic EL device electrical properties, such as complete creation of moving pictures, high color purity, low power consumption, and low driving voltage, are suitable for portable electronic equipment.
However, moisture may easily deteriorate an organic EL device. Therefore, an encapsulation structure preventing moisture entry is required.
Typically, a metal can or a glass substrate processed into a cap with an etched groove is used. According to this method, for moisture adsorption, a powder type desiccant is mounted in the groove or a film type desiccant is adhered in the groove with double-sided tape. However, the former method is complicated and costly. Additionally, substrate thickness increases and since the substrate is not transparent, the increased thickness may impede front emission. On the other hand, the latter process may not sufficiently prevent moisture entry and the desiccant may break easily during fabrication or use, thereby lowering durability and reliability, which renders mass production difficult. In addition to the above problems, etched glass may be easily damaged by external impact due to structural weakness.
Japanese Patent Laid-Open Publication No. Hei. 9-148066 discloses an organic EL device including a laminate having a pair of opposite electrodes with an organic light-emitting material layer interposed therebetween, an airtight container for preventing exposure of the laminate to the air, and drying means made of, for example, alkaline metal oxide, disposed in the airtight container. However, the organic EL device's thickness is increased by the airtight container's bulky shape. Also, opaqueness of the drying means renders the fabrication of a front emission type organic EL device difficult, even though the drying means is maintained in a solid state after adsorbing moisture. Additionally, as described above, the fabrication process is complicated and costly.